No matter how many pamphlets and press releases the Shanghai Tower can muster, it may never receive a greater PR boon than that provided by the two camera-wielding Russian daredevils who recently donned black hoodies and illicitly scaled its roof.

Since the pair, Vadim Makhorov and Vitaly Raskalov, posted a video of their ascent to Youtube on Wednesday, hundreds of thousands of viewers have learned two things about the tower: one, that it's the world's second tallest building, after the Burj Khalifa in Dubai; and two, that this makes it frighteningly, vertiginously tall.

The 632-metre Shanghai Tower (the pair climbed a further 18 metres up a crane on its roof) has been under construction in Shanghai's Lujiazui district, a gleaming financial centre directly across from the city's famous Bund, since 2008. It's set for completion later this year.

In the 1980s, Lujiazui was little more than a swath of grassy fields. Now it's a forest of skyscrapers.

It's difficult to glean from the video, in which the two men sneak into a poorly lit building site and climb up unadorned concrete stairs, but the tower is designed to be a sort of urban Elysium, packed with luxury hotels, offices and retail space. A slideshow on the website of Gensler, the American architecture firm behind the project, shows illustrations of the finished product, its glass-and-steel shell twisting up towards the sky like a giant cannolo.

Gensler calls the tower a "super-highrise precinct" – a series of individual neighbourhoods strewn over 142 vertically stacked acres, equivalent to nearly 80 football pitches. Each will surround a "light-filled garden atrium" designed, apparently, to "foster community and support daily life". The building twists through 120 degrees from its base to its top, helping it withstand the city's notoriously strong winds. Its elevators are designed to move at nearly 40mph.

Altogether, the stunt took the two men about 20 hours to complete, although the actual ascent took just two. They entered the tower under cover of dark, scaled the rooftop crane at daybreak, exchanged a high five – and then waited around for the light to improve, so they could best record the views down over the tops of the building's closest neighbours: the Jin Mao Tower and Shanghai World Financial Centre, rising above a thin cloud cover.

The Shanghai Tower will be an amazing building, if Gensler's plans hold true. But at that moment at the summit, one imagines, innovative architectural design felt as distant to the men as the ethereal cityscape below.